A conventional liquid crystal display is constructed generally to have a vertical drive circuit 101 and a horizontal drive circuit 102 disposed outside a display region 100 as shown in FIG. 6 (a).
As shown in FIG. 6(b), in the above-mentioned display region 100, display pixels 203 are provided, respectively, at intersections of a plurality of vertical signal lines 201 and a plurality of horizontal signal lines 202. The above-mentioned vertical signal lines 201 are connected to the above-mentioned vertical drive circuit 101, on the other hand, the horizontal signal lines 202 are connected to the above-mentioned horizontal drive circuit 102 via a video signal input line which is not shown. The above-mentioned display pixel is composed of a thin film transistor (for example, TFT: Thin Film Transistor) 204, a capacitor 205 and a pixel electrode 206. Numeral 207 denotes a capacitor line.
Assuming that, as a color liquid crystal display (hereinafter referred to simply as a liquid crystal display), there are such one configured to be capable of displaying colors by adding color filters made of resin containing paints or pigments having three primary colors of RGB to the above-mentioned liquid crystal display, or a projector or a projection television which uses three panels of liquid crystal displays without color filters and enables color display by inputting RGB lights and signals respectively thereto and composing an image therefrom, and further, a projector or a projection television which uses only one liquid crystal display panel likewise without color filters and enables color display by controlling the lights and signals to be inputted to the panel. Along with the proliferation of digital equipment represented typically by personal computers, demands for this color liquid crystal display are becoming versatile, and needs for enhanced image quality such as higher resolution and high fidelity color reproduction are increasing.
Therefore, also in the markets of projectors and projection televisions where transmission type liquid crystal displays have been dominant until now, demands for a reflective type liquid crystal display which has a capability for further improvement in the display image quality are increasing.
A reflective type liquid crystal display is more advantageous in that the following approaches can be achieved more easily than the transmission type liquid crystal display. (1) downsizing by decreasing a pixel area (a minimum display unit), (2) pixel multiplication without downsizing, and (3) to increase image smoothness by reducing a lattice-like black display area between pixels which is unavoidable due to the structure of the liquid crystal display.
However, if the pixel multiplication or the downsizing of the pixel area is carried out, there easily occurs rounding of a signal waveform due to fluctuation of a quantity of wiring coupling, or a noise from adjacent signal wiring, thereby introducing a risk of degrading the display image quality.
Therefore, there has been proposed a method for improving the image display quality by providing a grounded shield wire to a part or to the whole of the vertical signal lines and the horizontal signal lines so as to reduce a coupling noise with adjacent wiring or elements, and a noise entering therefrom (for example, refer to a patent document 1).
Patent Document 1: Japanese Patent Application Publication No. H06-11684.
That is, because the potential of the shield wire is constant, it is considered that a stable driving free of noise from external or the like becomes possible, thereby enhancing image quality.
However, as described in the above patent document 1 above, in such a structure in which the grounded shield wire is provided to part or the whole of the vertical signal lines and the horizontal signal lines, a wiring occupying density increases, and there is a risk that a defect such as a short circuit of wiring or the like takes place in each pixel.
Therefore, although certainly the image quality will improve, there is a risk that a product yield will decrease.
For example, if it is a memory such as DRAM or the like, a so-called redundancy remedy circuit is provided having a reserve block provided in advance to be switchable with a block having a defect by use of a fuse or the like, however, in the liquid crystal display, although the blocks are switched, this is not applicable as a color liquid crystal display in which the pixels and the color filters are disposed corresponding therebetween.